This invention relates to a digital anti-skid electronic control system for automotive vehicles wherein each controlled wheel is assigned a channel of its own which comprises an analog-to-digital (A/D) converter converting measured signals into digital values, with an arithmetic circuit being connected thereto which provides an output signal adapted to control a final control element which controls the braking pressure.
In such anti-skid electronic control systems, which obviously will have a substantial influence on the behavior of the vehicle, it must be ensured at all times that a malfunction in the anti-skid electronic control system does not adversely affect the behavior of the vehicle. Therefore, if such a malfunction occurs, the entire anti-skid control system must be disconnected for which purpose monitoring circuits are used. However, a monitoring circuit cannot be regarded as fail-safe if malfunctions occurring in the monitoring circuit may in turn be the cause that a defect in the anti-skid control system is not sensed. The probability of such an occurrence becomes higher the greater the number of the individual components in the monitoring circuit is the function of which is not continuously monitored.
In anti-skid control systems incorporating a digital arithmetic circuit, it is a further difficulty to find the criteria which permit the detection of a faulty output signal. Therefore, to be able to provide a monitoring circuit, it is above all necessary that facilities for error detection are provided.